The great thing about a good burger - the places that ask you wellness level are usually home-ground beef. Thus, less worries than the general storebought ground beef.
A fresh ground burger is amaaaazing. Medium works for me, with cheese, pleeease.

If I'm eating a thick-patty, medium rare, and I will gladly pay more, sign any illness waiver, or over tip in order to get one. With bacon, american cheese, and maybe some sauteed or raw red onion.
If I'm eating a thin-patty (Ann Arbor's Blimpie Burger, anyone?), it's a double with bacon, egg, and american cheese, with ketchup, a little mustard, and onion rings smashed right in.

I'm really not a fan of ground beef...something about ground meat really grosses me out, but I do enjoy a medium-well burger with onions and mushrooms every now and then. I can do rare steak, but if a burger has too much pink in it I'm really turned off.